LINQ : Joins

Here we are going to write Linq queries which will perform Left Join, Left Outer Join, and Cross Join. We have 2 tables Employess and Department. Employees has 5 rows and Department has 4 rows as shown below.

1. Join : Here is a query which will join Employees and Department and show the result.

Query :

var joins = from em in Employees

join d in Departments on em.DeptId equals d.DeptId

select new {Name = em.EmpName, Department = d.DeptName};

 Output :

2. Left Outer Join : Here is a query which will Left outer join Employess with Department and show the result.

Query :

var leftouterjoins = from em in Employees

                     join d in Departments on em.DeptId equals d.DeptId

                      into empd

                     from ed in empd.DefaultIfEmpty()

                     select new {Name = em.EmpName, 

                          Department = ed == null ? string.Empty:  ed.DeptName};

Output:

3. Cross Join : Here is a query which will cross join Employee table with Department and show the result.

Query:

  var crossjoins = from em in Employees

                   from d in Departments

                   select new {Name = em.EmpName, Department = d.DeptName};

Output: